Helped by a diet of “head-bashing heavy metal” and a Rubik’s Cube habit, the 21 year-old succeeded where his follow Devonian Liam Tancock, in the backstroke, and a host of other British Olympic hopefuls failed, winning ParalympicGB’s second gold medal of the opening day of competition.

The Olympic swimming team were the conspicuous failure of Team GB, managing just three medals in the pool, courtesy of Michael Jamieson’s silver and a brace of bronze for Rebecca Adlington. The Paralympians have matched that total in gold and silver within 24 hours, and Fox’s convincing performance will boost confidence that they are on course to at least repeat their Beijing achievement of fourth in the swimming medal table.

Fox, who has cerebral palsy, gave notice of his gold medal potential by lowering his own world record time by 0.59sec to 1min 09.86sec in the morning heat of S7 100 metres backstroke, confirmation that he was a justifiable favourite to go one better than the silver medal he won in Beijing.

That swim elicited a familiar roar from the partisan British supporters in a near-capacity 12,000 crowd, and they strained the temporary stands of Zaha Hadid’s pool in the final, when Fox surged into an early lead that he managed to defend despite running out of steam in the last 30 metres, winning in 1-10.46..

Afterwards he said he had not thought about being the first Briton to win gold in the London pool, but that he was proud to have led the way for the biggest swim team Britain has fielded at a Paralympics.

“It’s the biggest swimming team we’ve had and everyone’s backing everyone. We all know each other and everyone’s pushing each other on and saying 'good luck’ and 'well done’ and that’s all you need before a race, all your team-mates backing you.”

Fox, who, like Tom Daley, hails from Plymouth, had emerged for the final looking more boxer than swimmer, the hood of his robe raised and his iPod tuned to one of the heavy metal and punk bands that are his traditional accompaniment.

“I listened to a bit of heavy metal when I came out,” he said. “People really don’t like my taste music. It’s all head-bashing and stuff. A bit of Breaking Benjamin, Disturbed and Rise Against. People like no one’s ever heard of.”

By the time he emerged from the water Fox was far better known than his favourite bands, joining Sarah Storey as a rapturously received home winner. Watched by his parents, brother, aunts and uncles and cousins, he wagged his index fingers in celebration as he savoured the “awesome atmosphere”.

Fox, who relaxes by solving a Rubik’s Cube in 90 seconds, marginally longer than the 70 seconds it took him to win gold, said he was aware of the crowd even under water.

“I’m always in my zone when I walk out onto the playing field and after I’ve hit the wall, take in the moment. But you can hear the crowd from under the water. It’s awesome.”

Fox said he had hoped to lower his world-record mark again in the final but was content with gold after fearing that he would be overhauled by the fast-finishing Ukrainian Yevheniy Bohodayko, who took silver.

“At the turn for 50 I was feeling good but by about 75 my legs blew up,” he said. “There’s always that thing in your mind when you see someone in lane five snipping back at you and you’re dying inside, and you just want to finish. I stuck it through and hit the wall first.

“It comes around every four years and you just want to stop time for a second and feel the atmosphere.”

He may have another chance to savour victory in the 400m freestyle next Thursday, an event at which he is also the world record-holder.

“I’ve got more races but that’s a good start. My next main event is the 400 and I want to do my best in that because it’s going to be tough, with new rivals popping up. You never know who’s around the corner.”